Electronic Cigarette

ABSTRACT

An electronic cigarette comprises a control circuitry, a vaporizing unit, and a liquid store. The vaporizing unit is a unitary element comprising a plurality of fluidic channels configured to receive liquid from the liquid store. The fluidic channels are separated into a plurality of groups and each group of fluidic channels is thermally connected to a separate heating element. The control circuitry is configured to selectively operate one or more of the heating elements to selectively heat one or more corresponding groups of fluidic channels).

TECHNICAL FIELD

The present disclosure relates to electronic cigarettes, and in particular to a vaporizing unit for an electronic cigarette.

TECHNICAL BACKGROUND

The term electronic cigarette, or e-cigarette, is usually applied to a handheld electronic device that simulates the feeling or experience of smoking tobacco in a traditional cigarette. Common e-cigarettes work by heating an aerosol-generating liquid to generate a vapor that cools and condenses to form an aerosol which is then inhaled by the user.

Accordingly, using e-cigarettes is also sometimes referred to as “vaping”. The aerosol-generating liquid in the electronic cigarette usually comprises nicotine, propylene glycol, glycerin and flavorings.

Typical electronic cigarette vaporizers, i.e. systems or sub-systems for vaporizing the liquid, utilize a cotton wick and heating element to produce vapor from liquid stored in a capsule or tank. When a user operates the e-cigarette, liquid that has soaked into the wick is heated by the heating element, producing a vapor which cools and condenses to form an aerosol which may then be inhaled. To facilitate the ease of use of e-cigarettes, cartridges are often used. These cartridges are configured as “cartomizers”, which means an integrated component formed from a liquid store, a fluid transfer element (a wick), a heater and electrical connectors to establish a connection between the heating element and the power supply unit. The complexity of these traditional cartridges is often associated with drawbacks, such as inconsistent vapor generation (and, hence, inconsistent aerosol delivery to the user) and inconsistent performance over time.

In view of the above, the present disclosure seeks to provide an electronic cigarette with a high controllability in terms of vapor generation and consistent performance over time. Embodiments of the present disclosure seek in particular to provide an electronic cigarette which can provide a variable and optimized heating temperature to improve the vaporization of different liquids and/or which can provide control over the volume of vapor that is generated and/or in which automatic cleaning of a vaporizing unit is facilitated.

SUMMARY OF THE DISCLOSURE

According to a first aspect of the present disclosure, there is provided an electronic cigarette comprising a control circuitry, a vaporizing unit, and a liquid store, wherein: the vaporizing unit is a unitary element comprising a plurality of fluidic channels configured to receive liquid from the liquid store, the fluidic channels are separated into a plurality of groups, each group of fluidic channels is thermally connected to a separate heating element, and the control circuitry is configured to selectively operate one or more of the heating elements to selectively heat one or more corresponding groups of fluidic channels.

By selectively activating one or more of the heating elements, and thereby selectively heating one or more of the corresponding groups of fluidic channels, heating of liquid in the fluidic channels can be carefully controlled to ensure consistent vapor generation and performance over time. For example, the heating elements can be operated by the control circuitry to provide a back-up capacity within the vaporizing unit and/or to clean one or more fluidic channels which have become obstructed by debris/deposits. Furthermore, by providing the vaporizing unit as a unitary element, a simple construction is realized and manufacture and/or assembly of the electronic cigarette may be facilitated. By ‘unitary element’, it is meant that the vaporizing unit comprises a single unit and not, for example, a plurality of individual vaporizing units.

As used herein, the term “electronic cigarette” may include an electronic cigarette configured to deliver an aerosol to a user, including an aerosol for smoking. An aerosol for smoking may refer to an aerosol with particle sizes of 0.5 to 10 μm. The particle size may be less than 10 or 7 μm. The electronic cigarette may be portable.

In general terms, a vapor is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapor can be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms ‘aerosol’ and ‘vapor’ may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user.

The electronic cigarette may include a power supply unit. Each heating element may have a separate connection to the power supply unit and/or the control circuitry. The vaporizing unit may comprise a plurality of heating elements and the heating elements may be connected in parallel to the power supply unit. The electronic cigarette may comprise a plurality of heating circuits and each heating circuit may comprise one of the heating elements, a switch, the power supply unit, and the control circuitry. It will, therefore, be understood that each heating circuit has a separate connection to the power supply unit. Such an arrangement ensures that each heating element can be individually controlled by the corresponding heating circuit.

The fluidic channels may be heated along their entire length. A heating element may extend along the entire length of each fluidic channel to heat the fluidic channels along their entire length. This arrangement may facilitate vaporization of the liquid as it flows along the fluidic channels.

The fluidic channels may be heated at their outlets. A heating element may be positioned at an outlet of each fluidic channel to heat the fluidic channels at their outlets. This arrangement may reduce the likelihood of deposits and debris building up inside the fluidic channels along their length due to the fact the liquid is only heated and vaporized at the outlets of the fluidic channels.

As noted above, the vaporizing unit is a unitary element and in one example may comprise a monobloc element. For example, the fluidic channels may be formed inside a block-shaped component. The fluidic channels may have a circular cross-section.

In another example, the vaporizing unit is a unitary element formed by a plurality of component parts. For example, a plurality of plates may be used to form the vaporizing unit. The fluidic channels may be formed by plates arranged side by side to form a plurality of capillary channels. Such arrangements may simplify the structure of the electronic cigarette and promote the flow of liquid from the liquid store along the fluidic channels by capillary action.

In a further example, the vaporizing unit is a unitary element and may comprise a first horizontal layer and a second horizontal layer which may be arranged at a distance from each other to form a vaporization chamber therebetween. The first horizontal layer may be fluidically connected to the liquid store and the second horizontal layer may be configured to enable vapor generated in the vaporization chamber to leave a surface of the second horizontal layer.

The vaporizing unit may be a micro-electro-mechanical-systems (MEMS) vaporizing unit.

The vaporizing unit may comprise a first heating element, a second heating element and a third heating element. Each heating element may be associated with a separate group of fluidic channels. The control circuitry may be configured to selectively and independently operate the heating element associated with each group of fluidic channels to provide different operating states including activation, standby and deactivation. Such an arrangement provides enhanced control over vapor generation.

The control circuitry may further comprise a timer and a memory storing a program. The program may contain instructions regarding the selection of the operating state and a duration thereof. Such an arrangement facilitates the automatic execution of a program in which the duration of the operating states of the heating elements has been predetermined. This may help to ensure that the one or more groups of fluidic channels are heated by the corresponding heating elements for a suitable duration before the fluidic channels are deemed to be obstructed with debris or deposits and should be disabled.

The control circuitry may be configured to select a heating profile according to the type of liquid. For example, different liquids have different boiling points at which the liquids are vaporized, and the selection of a suitable heating profile ensures optimum heating and vaporization of different types of liquid.

The electronic cigarette may include a cartridge detection unit. The control circuitry may be configured to receive heating profile data from the cartridge detection unit and to determine the heating profile based on the received heating profile data. Such an arrangement facilitates automatic selection of an appropriate heating profile.

The control circuitry may be configured to calibrate the vaporizing unit to determine which heating element, or group of heating elements, should be activated. Optimum vapor generation can be achieved with such calibration.

The control circuitry may be configured to measure the electrical current supply to the heating elements. The control circuitry may be configured to measure the electrical resistance of the heating elements. The control circuitry may be configured to measure the temperature of the heating elements. Such an arrangement allows both vapor generation and the presence of liquid in the fluidic channels to be monitored.

The control circuitry may be configured to operate at least two heating elements to simultaneously heat at least two corresponding groups of fluidic channels to different temperatures. Such an arrangement may allow a group of fluidic channels obstructed by debris/deposits to be heated to a lower temperature than another unobstructed group of fluidic channels. This would allow the obstructed fluidic channels to be rinsed by the aerosol generating liquid in a ‘cleaning mode’, for example by preventing the heating of the aerosol generating liquid in the obstructed fluidic channels to a temperature at which vaporization of the liquid occurs and thereby allowing the debris/deposits to be flushed out of the fluidic channels by the aerosol generating liquid. Meanwhile, vapor production would still be assured by heating the aerosol generating liquid flowing in one or more unobstructed groups of fluidic channels to a temperature at which vaporization of the liquid occurs.

The electronic cigarette may further comprise a switch connected to the control circuitry. The control circuitry may be configured to disable a first heating element, e.g. by the switch, and to activate one or more further heating elements based on a measurement of one or both of the electrical current supplied to the first heating element and the electrical resistance of the first heating element. Such an arrangement provides for a segmented operation of the heating elements, and therefore a segmented heating of the groups of fluidic channels, in which the heating of the fluidic channels is disabled as the heating deviates from its desired performance range. This in turn offers the advantage that local overheating of dry or obstructed fluidic channels can be avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b are schematic views of an electronic cigarette according to an embodiment of the present disclosure configured to receive and enclose a replaceable cartridge;

FIG. 1 c is a schematic cross-sectional view of the electronic cigarette of FIGS. 1 a and 1 b;

FIG. 2 is a schematic view of an electronic cigarette according to another embodiment of the present disclosure, which is adapted to receive a replaceable cartridge within a mouthpiece portion;

FIGS. 3 a and 3 b are schematic views of another embodiment of an electronic cigarette according to the present disclosure, which is provided with a refillable liquid store and a separate vaporizing unit;

FIGS. 4 a and 4 b are schematic perspective and side views respectively of different examples of vaporizing unit suitable for use in an electronic cigarette according to the present disclosure; and

FIG. 5 is a schematic illustration of an electrical circuit for controlling one or more heating elements of an electronic cigarette according to the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings in which like features are denoted with the same reference numerals.

Referring to FIGS. 1 a to 1 c, there is shown an electronic cigarette 1 according to an embodiment of the present disclosure. The electronic cigarette 1 comprises a mouthpiece portion 2, a power supply portion 4 and an exterior housing 5. The power supply portion 4 can also be referred to as a main body 4 of the electronic cigarette 1, and is advantageously configured as a re-usable unit. The main body 4 comprises a power supply unit 9 and control circuitry 7 to operate the electronic cigarette 1.

The mouthpiece portion 2 comprises a liquid store 18 containing an aerosol generating liquid and a mouthpiece 6 having an outlet 8 for delivering vapor or aerosol to the user. The mouthpiece portion 2 may further comprise a cartridge seating 10 configured to receive a replaceable cartridge 12 which includes the liquid store 18.

The mouthpiece portion 2 can be provided with a separate mouthpiece housing 5 a which is configured to connect to a separable main body housing 5 b such that the cartridge 12 is enclosed inside the housing 5 of the electronic cigarette 1. The mouthpiece portion 2 and the main body 4 are connectable to each other by a releasable connection 14. The releasable connection 14 can, for example, be a threaded connection or a bayonet connection.

In another embodiment illustrated in FIG. 2 , the cartridge 12 may be provided with a mouthpiece 6 and a cartridge connector 11 for releasably attaching to a cartridge seating 10 of the main body 4 of the electronic cigarette 1.

Alternatively, as illustrated in FIGS. 3 a and 3 b, the electronic cigarette 1 may, instead of the cartridge seating 10 and the cartridge 12, be provided with a refillable liquid store 18 located in the mouthpiece portion 2 of the electronic cigarette 1.

The liquid contained inside the liquid store 18 can, for example, be propylene glycol or glycerin and may additionally contain other active ingredients such as nicotine, additives (such as acids) and flavors.

The electronic cigarette 1 further comprises a vaporizing unit 16 configured to vaporize the liquid from the liquid store 18 by heating the liquid to a temperature at which vaporization occurs (typically between 190° C. and 290° C.). The vaporizing unit 16 can be integrated inside a cartridge 12 together with the liquid store 18, as illustrated in FIG. 2 . Alternatively, and as illustrated in FIG. 3 b, the vaporizing unit 16 can be a separate component.

As best seen in FIGS. 4 a and 4 b which show different examples of a vaporizing unit 16 suitable for use with the electronic cigarettes 1 described above with reference to FIGS. 1 to 3 , the vaporizing unit 16 is fluidically connectable to the liquid store 18 and comprises at least one heating element 19, and preferably a plurality of heating elements 19. The vaporizing unit 16 also comprises a plurality of fluidic channels 20, for example capillary channels. The vaporizing unit 16 is a unitary element (i.e., constituted by a single unit) and can be configured as a separate part from the cartridge 12 and as a replaceable disposable unit attachable to a vaporizer seating 22 of the main body 4, as shown in FIG. 3 b. It can be advantageous to exclude the vaporizing unit 16 from the cartridge 12, as this simplifies the structure of the cartridge 12, makes it more economical to produce and facilitates recycling (due to the a more homogenous material construction with a limited amount of metals). However, it is also possible to provide the cartridge 12 with a combined liquid store 18 and an integrated vaporizing unit 16.

As illustrated in FIGS. 4 a and 4 b, different forms of the vaporizing unit 16 are possible, as the fluidic channels 20 can be formed by different methods. Common for all illustrated embodiments is that the vaporizing unit 16 is a unitary element and that the plurality of fluidic channels 20 is separated into a plurality of groups G1, G2, G3 . . . Gi, wherein each group of fluidic channels G1 to Gi is thermally connected to a separate heating element 19, which can be individually heated to heat a surface 20 a of the fluidic channels 20. This configuration is advantageous as it ensures high controllability of the vaporizing unit 16, and a consistent capacity and performance of the vaporizing unit 16 over a longer time period compared to prior art vaporizing units with fluidic channels 20 that are simultaneously heated and not divided into groups that can be heated separately. This is due to the fact that the flow of aerosol generating liquid from the liquid store 18 and through the fluidic channels 20 is reduced as a function of the activation time the vaporizing unit 16, due to debris/deposits building up over time in the fluidic channels 20.

In a first example illustrated in FIG. 4 a, the fluidic channels 20 can be configured as tubular (closed) channels 20 arranged inside a block-shaped component 24. The block-shaped component 24 is a unitary element, preferably a monobloc element, and may be formed from electrically conductive material such as silicon, doped ceramic, metal-ceramic, filter ceramic, semiconductor, germanium, graphite, semi-metal and/or metal. The fluidic channels 20 can be heated along their entire length via their outer surface 20 a, or alternatively only at their outlets 26. In the former case, resistive heating elements 19 can be embedded in the block-shaped component 24 so that they extend along the length of the fluidic channels 20 and are substantially parallel thereto. The vaporizing unit 16 may also comprise electrical connectors (not shown), configured to electrically connect the vaporizing unit 16 to the power supply unit 9 and control circuitry 7.

In a second example illustrated in FIG. 4 b, the fluidic channels 20 can be formed by plates 32. The plates 32 are provided at a distance d from each other in order to create a gap sufficient to draw liquid into the fluidic channels 20 from the liquid store 18 by capillary action. One or more of the plates 32 are preferably heatable and can be provided in a high-resistivity material, for instance Titanium, Nickel, Chrome,

Stainless steel or an alloy including at least one of these materials. The plates 32 are provided with a first end 34 configured for electrical connection to the power supply unit 9 and control circuitry 7 and a second end 36 configured as a vapor outlet. The vaporizing unit 16 can thus be formed as an elongate extension of heatable plates 32. The plates 32 may be held together as a stack by at least one insulating element 40. The stacked structure can be easily assembled as plates 32 stacked side-by-side and enables small fluidic channels 20 to be formed in a simple manufacturing process and with precision. With this arrangement, the vaporizing unit 16 is once again formed as a unitary element.

To enable groups of the fluidic channels 20 to be separately heated, the vaporizing unit 16 comprises fluidic channels 20 thermally connected together in at least three different groups; a first group G1, a second group G2 and a third group G3.

However, there can be more than three groups, if desired, for example as shown in FIG. 4 a. Each group G1 to Gi may comprise any desired number of fluidic channels 20.

To achieve an accurate control of the vaporizing unit 16, the vaporizing unit 16 and the control circuitry 7 may be configured as a micro-electro-mechanical-systems (MEMS) component. The MEMS component structure provides a compact control circuitry to control the flow and vaporization from the fluidic channels 20. This further enables the electronic cigarette 1 to precisely control parameters such as vapor volumes and particle size.

Each group G1 to Gi of fluidic channels 20 is preferably configured to be operated (or heated) in a uniform way. To this effect, each group G1 to Gi of fluidic channels 20 is preferably heated by a corresponding one of the heating elements 19 (H1 to Hi).

The control circuitry 7 is further configured to set the heating elements H1 to Hi into different operating states, the operating states comprising activation, standby and deactivation. The control circuitry 7 is also configured to change the operating states of the different heating elements H1 to Hi over time.

The plurality of groups G1 to Gi of fluidic channels 20 enable the electronic cigarette 1 to provide a consistent amount and composition of vapor over time. This addresses the problem that over time, some of the fluidic channels 20 may become obstructed due to debris/deposits building up within the fluidic channels 20. If an obstructed fluidic channel 20 continues to be heated, a reduced amount of vapor is produced while the temperature increases (due to reduced flow of aerosol generating liquid through the fluidic channel 20) and the composition of the vapor may degrade and become unpleasant to the user. Having a plurality of groups G1 to Gi of fluidic channels 20 enables a sequential activation, thus creating a backup capacity in the vaporizing unit 16.

With reference to the schematic illustration of the electrical circuit shown in FIG. 5 , this is achieved by a controller 50 in the control circuitry 7 which is connected to and configured to selectively activate switches S1 to Si connected to a corresponding one of the heating elements H1 to Hi. The control circuitry 7 can comprise a first switch S1 that automatically deactivates the heating element H1 when the fluidic channels 20 in the corresponding first group G1 are determined to be obstructed.

Initially a first group G1 of fluidic channels 20 can be heated by closing the switch S1 to activate the corresponding heating element H1, while a second group G2 and a third group G3 of fluid channels 20 are deactivated. Then, once the first group G1 of fluidic channels 20 is determined to be obstructed, the at least one heating element H1 in thermal contact with the first group G1 of fluidic channels 20 can be switched to a deactivated/standby state by opening the switch S1 and a second heating element H2 in thermal contact with a second group G2 of fluidic channels 20 can be activated by closing the switch S2. During this time, the third group of fluidic channels G3 can be in a standby mode which ensures the production of vapor for another, later, time interval.

The control circuitry 7 can be configured to determine the amount of time for which each group G1 to Gi of fluidic channels 20 should be heated by the corresponding heating elements H1 to Hi.

According to a first embodiment, the controller 50 can determine the obstruction of the fluidic channels 20 by measuring the period of time for which each group G1 to Gi of fluidic channels 20 has been heated. The control circuitry 7 further comprises a memory 52 configured to store a time threshold. The time threshold may advantageously be based on historical data of the vaporizing unit 16 and for different types of aerosol generating liquids to provide threshold data on the average time that the fluidic channels 20 typically take to become obstructed. Additionally, to provide an even more accurate estimation, the applied temperature setting and variations thereof over time can be measured by the controller 50 and included in the data to be compared against the threshold data. The temperature has an impact on the obstruction, as the higher the temperature used, the more debris is usually formed in the fluidic channels 20.

Alternatively, the memory 52 of the control circuitry 7 may contain instructions regarding the selection of type of operating mode and the duration. This will automatically enable the execution of a program determining a default program of how long each group G1 to Gi of fluidic channels 20 could be heated before they are deemed to be obstructed and should be disabled by the controller 50. Hence, the controller 50 is configured to calculate an allowable amount of operating time based on a plurality of characteristics (including, e.g., temperature setting and liquid type) and to disable the corresponding heating element H1 to Hi via the corresponding switch S1 to Si once the time has elapsed. This saves processing capacity from the control circuitry 7, as no continuous measurement other than time is needed.

As another alternative, the control circuitry 7 may be configured to measure the electrical resistance of a heating circuit associated with each of the groups G1 to Gi of fluidic channels 20 in operation and to compare a measured resistance value Rm with a reference value Rv. The measured resistance value Rm is indicative of the level of obstruction in the fluidic channels 20. The electrical resistance of the heating circuit increases with a higher temperature. Hence, an increased temperature (and increased resistance) is indicative of an absence of liquid or an obstruction in the fluidic channel 20, as liquid present in the fluidic channels 20 tends to cool the heating element H1 to Hi as energy from the heating element H1 to Hi is consumed in the vaporization of the liquid. The controller 50 may therefore be configured to measure the current flow and/or the electrical resistance of each group of heating circuits. This has the advantage that both the vapor production and the presence of liquid can be precisely monitored.

In the embodiment where the controller 50 is configured to measure the electrical resistance of the heating element H1 to Hi, the memory 52 contains a resistance threshold, such that the controller 50 can disable the heating element H1 to Hi when the measured resistance corresponds to the threshold.

In yet another embodiment, the electronic cigarette may further comprise a communication unit 56, via which data comprising operating instructions for the heating elements H1 to Hi can be transferred from a computing device to the controller 50.

Another advantage of the present disclosure is that the vapor volume can be modified by the controller 50. The user may for instance want to vary the amount of vapor or aerosol delivered by the electronic cigarette 1. The controller 50 may therefore also be configured to activate a variable number of groups H1 to Hi of heating elements 19 to simultaneously heat a plurality of groups G1 to Gi of fluidic channels 20.

The electronic cigarette 1 may also be configured to heat different groups G1 to Gi of fluidic channels 20 simultaneously, but at different temperatures. This would enable the rinsing of some channels 20 in a ‘cleaning mode’ while the main vapor volume is generated by heating aerosol generating liquid flowing through one or more other groups G1 to Gi of the fluidic channels 20.

The electronic cigarette 1 may be further configured to provide different heating profiles for different types of liquids and flavors. The aerosol generating liquid typically comprises a mix of propylene glycol (PG) and vegetable glycerin (VG). When these liquids are mixed, the boiling point of the composition corresponds to a combination of the respective boiling points. The new boiling point of the combined liquid formulation is then different from the individual boiling points of the original liquids.

Typically, propylene glycol has a boiling point 188.2° C. and a viscosity of 0.042 Pa·s. Glycerin on the other hand has a boiling point 290° C. and a viscosity of 1.412 Pa·s. Capillary penetration in the fluidic channels 20 is resisted by viscous forces. These significant differences impact the ease with which the liquid can flow through the fluidic channels 20.

Because of the variation of vaporization temperature between liquids, the temperature setting of the heating elements 19 should preferably be adapted to the vaporization temperature of the liquid composition.

To accommodate aerosol generating liquids having different viscosities, the fluidic channels 20 can be arranged in groups G1 to Gi where each group is provided with a different cross-sectional area. For example, one group G1 of fluidic channels 20 could work best with a first liquid and another group G2 with a second liquid. This allows the vaporizer to adapt to different liquid compositions, as Propylene Glycol and Vegetable Glycerin and combinations thereof have widely spread different viscosities and boiling temperatures. Each of the different groups G1 to Gi of fluidic channels 20 may include channels 20 having different diameters.

The control circuitry 7 of the electronic cigarette 1 is further configured to enable selective activation of the groups of channels G1 to Gi depending on the type of liquid.

The type of liquid can either be manually inputted on a control interface 54 of the electronic cigarette 1, or on a remote computing device (e.g. a smartphone-type device with Bluetooth connection) connected via wired or wireless link to the control circuitry 7 of the electronic cigarette 1. Alternatively, the electronic cigarette 1 may comprise a cartridge detection unit 60 configured to sense the type of cartridge and thus the type of liquid. For example, the cartridge detection unit 60 may comprise a cartridge reader which is configured to read an indicium (such as a computer-readable code) on a cartridge 12 and to send instructions to the controller 50 about the type of cartridge 12.

Furthermore, the use of different flavors also has an impact on the vaporization temperature, because each type of flavor has a different ideal vaporization temperature. This is because larger particle sizes stay in the sensory area in the user's mouth, while smaller sized particles travel deeper into the user's lungs.

Different particle sizes can be achieved by controlling any one or more of:

the size (e.g. cross-sectional area) of the fluidic channels 20;

the length of the fluidic channels 20;

the temperature of the heating elements 19 (and, hence, the vaporization temperature);

the temperature of the generated vapor (because when the temperature decreases, the vapor condenses by particles adhering to each other); and

the flow of vapor, e.g. the speed of vapor in the fluidic channels 20.

The use of different flavors in combination with different ratios of propylene glycol and vegetable glycerin have different optimal temperatures where the sensory effect is best experienced.

The vaporizing unit 16 is configured to produce a consistent and controlled particle size. The temperature and the size of outlets 26 of the fluidic channels 20 define the particle size. The vaporizing unit 16 can therefore be provided with groups G1 to Gi of fluidic channels 20 having different sized (e.g. diameter) outlets 26. The length of the fluidic channels 20 may also be different from one group of channels 20 to another.

The memory 52 can also include indications of which liquid type is to be used with which heating element H1 to Hi, i.e., with which group G1 to Gi of fluidic channels 20.

Alternatively, the controller 50 can be configured to calibrate the vaporizing unit 16 to determine which heating elements H1 to Hi should be used for heating the aerosol generating liquid. This can be achieved by a calibration cycle in which all of the heating elements H1 to Hi are activated to heat all of the corresponding groups G1 to Gi of fluidic channels 20, and wherein the resistance and temperature is defined. Alternatively, a test run can be activated during which the user can select the mode that is the most satisfactory.

The skilled person will realize that the present disclosure is by no means is limited to the described exemplary embodiments. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Moreover, the expression “comprising” does not exclude other elements or steps. Other non-limiting expressions include that “a” or “an” does not exclude a plurality and that a single unit may fulfil the functions of several means. Any reference signs in the claims should not be construed as limiting the scope. Finally, while the disclosure has been illustrated in detail in the drawings and in the foregoing description, such illustration and description is considered illustrative or exemplary and not restrictive; the disclosure is not limited to the disclosed embodiments. 

1. An electronic cigarette comprising a control circuitry, a vaporizing unit, and a liquid store, wherein: the vaporizing unit is a unitary element comprising a plurality of fluidic channels configured to receive liquid from the liquid store, the fluidic channels are separated into a plurality of groups, each group of fluidic channels is thermally connected to a separate heating element, and the control circuitry is configured to selectively operate one or more of the heating elements to selectively heat one or more corresponding groups of fluidic channels.
 2. The electronic cigarette according to claim 1, wherein the fluidic channels are heated along their entire length.
 3. The electronic cigarette according to claim 1, wherein the fluidic channels are heated at their outlets.
 4. The electronic cigarette according to claims 1, wherein the fluidic channels are formed in a block-shaped substrate.
 5. The electronic cigarette according to claim 1, wherein the fluidic channels are formed by plates arranged side by side to form a plurality of capillary channels.
 6. The electronic cigarette according to claim 1, wherein the fluidic channels have a circular cross-section.
 7. The electronic cigarette according to claim 1, wherein the vaporizing unit is a micro-electro-mechanical-systems (MEMS) vaporizing unit.
 8. The electronic cigarette according to claim 1, wherein the vaporizing unit comprises a first, a second and a third heating element, each heating element being associated with a separate group of fluidic channels, and the control circuitry is configured to selectively and independently operate the heating element associated with each group of fluidic channels to provide different operating states including activation, standby and deactivation.
 9. The electronic cigarette according to claim 8, wherein the control circuitry further comprises a timer and a memory storing a program, wherein the program contains instructions regarding the selection of the operating state and a duration thereof.
 10. The electronic cigarette according to claim 1, wherein the control circuitry is configured to select a heating profile according to the type of liquid.
 11. The electronic cigarette according to claim 10, wherein the control circuitry is configured to receive heating profile data from a cartridge detection unit and to determine the heating profile.
 12. The electronic cigarette according to claim 8, wherein the control circuitry is configured to calibrate the vaporizing unit to determine which heating element, or group of heating elements, should be activated.
 13. The electronic cigarette according to claim 8, wherein the control circuitry is configured to measure electrical current supply to the heating elements.
 14. The electronic cigarette according to claim 1, wherein the control circuitry is configured to operate at least two heating elements to simultaneously heat at least two corresponding groups of fluidic channels to different temperatures.
 15. The electronic cigarette according to claim 1, further comprising a switch connected to the control circuitry, wherein the control circuitry is configured to disable a first heating element and activate a second group of heating elements based on a measurement of one or both of the electrical current supplied to the first heating element and the electrical resistance of the first heating element. 